Electric regulator



Juue \0 1930, H. M. STOLLER ELECTRIC REGULATOR Original Filed July 24,1919 Patented June 10, 1930 UNITED STATES PATENT OFFICE HUGH I. BTOLLEB,OF MOUNTAIN LAKES, NEW JERSEY, ASSIGNOR TO' WESTERN ELEGIRIC COKPANY,INCORPORATED, NEW YORK, N. Y., A CORPORATION OF NEW ELECTRIC REGULATOROriginal application fled. July 84, 1919, Serial No. 318,039. Dividedand this application fled August 90, 1985. Serial No. 51,818. RenewedDecember 27, 1929.

This invention relates to a novel type of regulator which is applicablein general for the regulation of electric circuits, and is particularlyadapted for, controlling the frequency of an alternating currentgenerator.

2 This ap lication is a division of my revious app 'cation, Serial No.313,039, ed Jul 24, 1919. y

I file regulator provided according to the present invention is of thethermionic typeand comprises avacuum tube containing e ectrodes. As iswell known in the art, the cathode of a vacuum tube serves as a sourceof electrons that travel to the anode or plate 5 electrode and theamount of this electron stream or space current depends upon severalfactors, primarily upon t e temperature of the cathode, an increaseintem erature producing a larger space current. t 1s also well so knownthat changes in thetemperature of a cathode create much more thanproportional changes in the space current and consequently intheinternal impedance of the tube, so that a vacuum tube may be made torespond very as readil to changes in the, temperature of the oath e.

In accordance with this invention, the frequency of the voltagegenerated by an alternating current generator is regulated by emsoploying a thermionic regulator to control the drivin source of thegenerator. If the generator is driven by a motor, the regulator may beinserted in circuit wlth an exciting winding of the motor, and thecathode of the tube may be supplied with current WhlCh varies as thefrequency of the generated current. One way in WhlCh the heating currentmay be made to restpond to the frequency, is to sup ly the ca ode vwithsaid current through a circuit tuned to a frequency preferably higherthan the maximum frequency desired from said machine. The intensity ofthe'current in this tuned circuit Wlll depend upon the frequenc of thecurrent so that the temperature 0 the cathode and consequently theefiective impedance of the tube will respond to variations of thefrequency ted, and will regulate the speed of the i motor so as to bringabout the dev sired regulation.

As is well known in the art, the space current of a vacuum tube at firstincreases very rapidly with increase'in plate voltage, but after acertain value of the plate voltage, depending upon the temperature ofthe cathode, is reached, the space current remains substantiallyconstant regardless of further increase. in plate voltage. In utilizinga vacuumtube as a regulator, it has been found preferable to have thetube operate on that part of the curve abovedescribed where a widevariation in plate voltage will not produce any appreciable change inthe space current.

The electric regulator of the thermionic type possesses many advantagesover regulators of other types in that it is simple, efiicient, li ht inweight and has no moving arts. ther advantages will be apparent trom thedetailed description of this inven- For a better understanding of thisinvention, reference is made to the following detailed description inconnection with the accompanying drawing in which Fig, 1 illustrates athermionic regulator of thi invention adapted to regulate the frequencof the current generated by an A. C. machine, and Fig. 2 is'acurveshowing how the current in the tuned circuit changes with theimpressed frequency.

Referring to Fig' l, is an alternating current generator having awinding 26, which is supplied with current from an exciter 27. Thegenerator 25 is driven by a motor 28. The anode 32 and cathode 33 of thevacuum tube 34 are connected in circuit with an exciting aiding winding35 of the motor 28, across the leads 37 and 38. Connected across thebrushes of the A. 0. machine 25 are a condenser 39 anda winding 40 of atransformer 41. Thesecondary of transformer41 is connected to theterminals of cathode 33. The capacity of condenser 39 and the inductanceof winding 40 are preferably of such values as to form a circuit tunedto a frequency higher than the maximum fre uency generated by themachine 25. The heating current for cathode 33, therefore, depends uponthe strength of the alternating current flowing through condenser 39 andwinding 40.

As is well known in the art, the strength of the current in a circuitcontaining inductance and capacity, is a maximum for the frequency ofcurrent to which the circuit is tuned and decreases rapidly in value asthe frequency changes to other values.

Fig. 2 illustrates a characteristic curve such as the tuned circuitcontaining condenser 39 and winding 40 may have. The ordinates representvarious values of current while the abscissa: represent the variousvalues of the impressed frequency. As stated above, it is preferablethat the condenser 39 and inductance 40 be tuned to a higher value offrequency than will be met in the operation of generator 25 so that thevariation in frequency, due to changes in load, for example, would bewithin the range of P, and P on this curve. As may be seen from thedrawing, the curve is very steep between these two points a smallincrease in frequency of the generator producing a very large increasein the value of the current flowing through the tuned circuit.

The manner in which the regulation is obtained in Fig. 1 may now bedescribed as follows:

With the condenser 39 and inductance 40 so adjusted that the frequencyof the current of generator 25 has a value intermediate the points P andP on the characteristic curve of the circuit, suppose that the frequencyof the current generated by generator 25 should suddenly increase. Thisincrease of frequency, as shown by the above mentioned characteristiccurve, would produce a much greater change in the current flowingthrough inductance 40. This increase in current would be impressedthrough thansformer 41 on the cathode 33, increasing its temperature andincreasing the current in the aiding winding 35 of motor 28. This changein the current through aiding winding 35 would slow down the speed ofthe generator 25 so as to restrict to a very small value the increase infrequency. It follows therefore, that any change in the frequencygenerated by generator 25 will so change the current through the aidingwinding 35 of the motor 28, that the change in frequency would berestricted to a small value, thereby enabling the frequency of generator25 to be maintained at a substantially constant value in spite ofchanges in the circuit conditions of the generator.

It is obvious that this invention is not limited to the particular formabove described but maybe considerably modified without departing in anywise from the essential novel principles inherent in this invention asdefined in the appended claims.

lVhat is claimed is: V

1. In combination, an alternating current generator, and means forregulating the frequency of the current generated thereby, said meanscomprising an electric discharge device having a (plurality ofelectrodes, connections from sai generator for supplying space currentbetween two of said electrodes, a path comprising inductance andcapacity tuned to a frequency differing from the normal frequency ofsaid generator, means for controlling through the intermediary of saidpath a characteristic of one electrode of said device in response tovariations in the frequency of the current generated, and meanscontrolled by the resulting variations in the space current of saiddevice for controlling said generator.

2. In combination, an alternatin current generator, a motor for drivingsai generator, a field winding for said motor, and means for regulatingthe frequency of the current produced by said generator, said meanscomprising an electric discharge device having a plurality ofelectrodes, connections from said generator for supplying space currentbetween two of said electrodes, a path comprising inductance andcapacity tuned to a frequency differing from the normal frequency ofsaid generator connected across the generator terminals independently ofthe motor circuit, means for controlling through the intermediary ofsaid path the temperature of an electrode of said device in res onse tovariations in the characteristic of sai generator, and connections forsupplying the space current of said device to said field winding forcontrolling said generator.

3. In combination, an alternating current generator, and means forregulating the frequency of the current generated thereby, said meanscomprisin an electric discharge device having a cat ode and an anode,connections from said generator for supplyin space current between twoelectrodes, a pat comprising inductance and capacity tuned to afrequency differing from the normal frequency of said generator, asecond inductance inductively coupled to said first inductance andconnected to said cathode for supplying heating current thereto, thevalue of which varies in accordance with the frequency of the currentgenerated, and means controlled by the resulting variations in the spacecurrent of said device for controlling said generator.

4. In combination, an alternatin current generator, a motor for drivinsai generator, said motor having an exclting winding, and means forregulating the frequency of the current generated, said means comprisingan electric discharge device having an anode and a thermionic cathode,connections from one electrode of said device to one terminal of saidgenerator, and connections from the other electrode of said devicethrough said exciting winding to the other terminal of said generatorfor supplying exciting current to said winding, a path comprisinginductance and capacity tuned to a frequenc differing from the normalfrequency 0 said generator connected to the terminals of said generator,and means for supplyin heating current to said cathode through t eintermediary of said path.

5. In a regulator system, an alternating current generator, an electrondischarge device having a cathode and an anode connected across theterminals of said generator, means comprising a tuned circuit connectedto the output circuit of said generator for heating said cathode inaccordance with the frequency of said generator, and means forcontrolling the frequency of the generator in accordance with the spacecurrent of said device.

6. In a regulator system, a motor having a regulating field winding, asource of alternatin current having a frequency varying according to themotor speed, a space discharge device having the anode and cathodethereof connected to said source of alternating current for receivingspace current therefrom, and means for controlling said device accordingto the frequency of said source to govern said field winding so as tomaintain the motor speed constant.

7. In a regulator system, a motor a source of alternatin current havinga frequency varying accor ing to the motor speed, a space dischargedevice having the anode and cath- Ode thereof connected to said sourcefor receiving space current therefrom, means comprising a tuned circuitfor controlling said device according to the fre uency of said source,and means governed y said device for maintaining the motor speedconstant.

8. In a regulator system, a dynamo-electric machine, a source ofalternatin current having a frequency varying accor ing to acharacteristic of said machine, a space discharge device having theanode and cathode thereof connected to said source for receiving spacecurrent therefrom, means for controlling said device according to thefrequency of said source, and means governed by said device formaintaining said characteristic of the machine constant.

9. In a regulator system, a dynamo-electric machine, a source ofalternatin current having a frequency varying accor ing to acharacteristic of said machine, a space discharge device having theanode and cathode thereof connected to said source for receiving spacecurrent therefrom, means comprising a tuned circuit for controlling saiddevice according to the frequency of said source, and means governed bysaid device for maintaining said characteristic of the machine constant.

-J. In a regulator system, a dynamo-elec- I tric machine, a source ofalternating current having a frequency varying according to acharacterlstlc of said machine, a space (115- charge device havingalternating current connected to the anode and cathode thereof,

means for controlling said device according to the frequency of saidsource, and means governed by said device for maintaining thecharacteristic of said machine constant.

11. In a regulator system, a motor, a source of alternating currenthaving a frequency varying according to the speed of the motor, a spacedischarge device having alternating current connected to the anode andcathode thereof, means for controlling said device according to thefrequency of said source, and means governed by said device formaintainin the motor speed constant.

In witness whereof I hereunto subscribe my name this 17th day of August,A. D.

HUGH M. STOLLER.

